OUSA events, clubs and recreation general manager Jason Schroeder said the organisation had done relief concerts before on a smaller scale.
Everyone had been devastated to see the scale of destruction resulting from Cyclone Gabrielle in the North Island and they wanted to see what they could do to help, Mr Schroeder said.
A relief concert made sense as OUSA already had the equipment and infrastructure for running O Week events, he said.
New Zealand artists were flying in from across the country, including Lee Mvtthews and Muroki.
The line-up also featured Dunedin bands such as Ha the Unclear, Tahu and the Takahes, Emily Alice, and Wax Mustang.
The event would also be something of a homecoming for former Dunedin band Summer Thieves, who are now based in Auckland.
The bands were basically playing for free, with OUSA just covering their costs, Mr Schroeder said.
Food would be available and the weather was looking good.
"I’m hoping it will be a really nice day for the city as well as a good fundraiser," Mr Schroeder said.
The concert would be held tomorrow between 2pm and 7pm on the Union Lawn.
A building at the site had come down over summer and it had really opened the site up, enabling it to be used for more events.
It was likely it would be used for more orientation events in the future.
Tickets are $30 for adults and $10 for children.
Profits will go to the Red Cross.
